This invention relates to a nut assembly used to bolt an instrument or the like to a member or a portion of which hands cannot reach the interior or the back.
FIG. 3 shows a conventional nut assembly used to fasten an instrument or the like to a member or a portion, the back of which is not accessible.
The nut assembly 1 comprises a nut 5 having a threaded through-hole 2 and pins 3 on both sides and formed at one end thereof with an inclined guide surface 4 for causing the nut to rotate when pushed by a bolt A, and a frame 9 having a pair of opposed arms 8 provided on both sides of a flange portion 7 having a bolt hole 6 at the center. By supporting the pins 3 in elongated holes 10 formed in the arms 8, the nut 5 is mounted between the opposed arms 8 so as to rotate about the pins 3 and to be slidable along the elongated holes 10.
For the nut assembly 1, lugs 11 are provided on both sides of the nut 5 near the outer peripheries of the arms 8 so that, with the nut 5 positioned at the tips of the elongated holes 10, the nut 5 can turn only 90xc2x0 in one direction from the position in which the longitudinal direction of the nut 5 is aligned with the longitudinal direction of the arms 8 and can slide along the elongated holes 10 from the position in which the longitudinal direction of the nut 5 is perpendicular to the longitudinal direction of the arms 8. Further, at the tips of the arms 8, lugs 12 are provided, and the lugs 11 are adapted to engage the lugs 12 when the longitudinal direction of the nut 5 is aligned with the longitudinal direction of the arms 8.
The pins 3 provided on the sides of the nut 5 each have a shaft with a smaller diameter than the width of the elongated hole 10 and a head at one end of the shaft, the head having an oval shape with such a width as to allow the head to pass through the elongated hole 10 and a length larger than the width of the elongated hole 10. Thus, with the nut 5 located in its lower position and aligned with the arms 8 (as shown in FIG. 3), the pins 3 can be inserted into the elongated holes 10 in the arms 8. But, with the nut 5 perpendicular to the arms 8, the pins 3 will not come out of the elongated holes 10.
The flange portion 7 of the frame 9 is rectangularly shaped. Around the bolt hole 6 in the flange portion 7, a bolt-guiding wall 13 for axially guiding a bolt A inserted through the bolt hole 6 so as for the bolt to be reliably threaded into the threaded hole 2 is provided so as to protrude toward the bolt hole 6.
FIGS. 4 and 5 show the conventional nut assembly 1 inserted into a hole 15 formed in the member B to mount an instrument (not shown) to the member using a bolt. FIG. 6 shows how an instrument C is fastened to the member B by means of a bolt A tightened into the nut assembly 1. As shown in FIGS. 4 and 5, the nut assembly 1 is inserted into the hole 15 with the nut 5 first and further pushed in until the flange portion 7 abuts the surface of the member B: With an instrument C superposed on the flange portion 7 of the nut assembly 1 (as shown in FIG. 6), the bolt A is inserted into a hole D of the instrument C while pushing the inclined guide surface 4 with the tip of the bolt, thereby turning the nut 5 by 90xc2x0. The tip of the bolt is guided into a tapered guide surface 14 of the nut 5 so as to threadedly engage female threads of the threaded hole 2. When the bolt is turned further, the nut 5 is pulled close. The mounting is now complete.
However, with the conventional nut assembly 1, the diameter and shape of the hole 15 formed in the member B is not always adapted to the nut. In particular, if it is slightly deformed or is slightly smaller, when inserted into the hole 15, as shown in FIGS. 4 and 5, the portions of the arms 8 near the flange 7 will be pushed inwardly as shown in FIG. 3 at P1. If such force is applied, the tips of the arms 8 tend to spread with the corner portions 16 of the nut 5 as fulcrums.
With the nut 5 aligned with the arms 8 in a lengthwise direction, if the nut 5 is raised by the arm spreading force off the lower ends of the elongated holes 10, the arms 8 can be freed from the restraint by the heads of the pins 3. This will lead to an unfavorable situation in which the arms 8 disengage from the pins 3, so that the nut 5 comes off the arms 8.
A solution in which the large-diameter portions at the tips of the pins 3 are made more rigid to prevent the nut 5 from coming off has been proposed. But this may hinder smooth turning of the nut.
Also, when handling the nut assembly 1 by hand, one may be caught by the tips of the arms 8. This will spread the tips, causing the nut 5 to come off.
According to this invention, there is provided a nut assembly comprising a pivotable nut having a threaded through-hole and a pin on each side thereof, and a frame having a flange portion formed with a bolt hole and an opposed pair of arms extending from both sides of the flange portion, the arms each being formed with an elongated hole, the nut being formed at one end thereof with an inclined guide surface for pivoting the nut when pushed by a bolt, the nut being pivotably and slidably mounted between the arms with the pins received in the elongated holes formed in the arms, characterized in that the arms having free end portions bent inwardly at an angle toward each other.
According to this invention, the arms each include a first portion having an angle of 90xc2x0 or over with respect to the flange portion and a second portion continuing from the first portion and inwardly bent from the first portion. In the illustrated embodiment, the arms have alsmost their entire lengths bent inwardly at an angle toward each other.
In this invention, since the nut is sandwiched between the arms, it is necessary that the arms have resilience. Normally, a metallic thin plate or a synthetic resin is used. If larger resilience is required, the metallic thin plate may be subjected to hardening such as heat treatment.
Other features and objects of the present invention will become apparent from the following description made with reference to the accompanying drawings, in which: